Rubber printing blankets and process for removing and cleaning glazes therefrom

ABSTRACT

A process of removing glaze from printing blankets, preferably comprising the steps of (a) placing the blankets in a saturated water solution of a mineral acid salt in combination with either potassium sodium tartrate or an organic acid; (b) maintaining the temperature of the solution with the blankets therein just under 212* F. for a period of approximately 45 minutes to one hour; (c) then removing the blankets from the solution and rinsing them with water; (d) removing water spots from the facing of the blankets; and (e) then drying the blankets.

United States Patent [151 3,642,537 Garms Feb. 15, 1972 [54] RUBBER PRINTING BLANKETS AND 2,410,415 11/1946 Jones ..lO1/425 PROCESS FOR REMOVING AND 2,747,506 5/1956 Ross et al.. .....101/424 CLEANING GLAZES THEREFROM 3,355,324 11/1967 Catzen ..134/29 [72] Inventor: Frederick L. Garms, 961 Avenue A",

Battle Creek, Mich. 49015 7 [22] Filed: Feb. 2, 1970 [21] App]. N0.: 8,075

[52] US. Cl ..l34/28, 134/38, 134/40, 134/42, 101/424 [51] Int. Cl. ..B08b 3/08, B08b 3/10 [58] Field ofSearch ..134/2, 3,25, 26-30, 1134/3840, 42; 101/423, 424, 425

[56] References Cited UNITED STATES PATENTS 2,326,837 8/1943 Coleman 134/27 Primary ExaminerMorris O. Wolk Assistant Examiner-Joseph T. Zatarga Att0rneyRoy A. Plant [5 7] ABSTRACT A process of removing glaze from printing blankets, preferably comprising the steps of (a) placing the blankets in a saturated water solution of a mineral acid salt in combination with either potassium sodium tartrate or an organic acid; (b) maintaining the temperature of the solution with the blankets therein just under 212 F. for a period of approximately 45 minutes to .one hour; (c) then removing the blankets from the solution and rinsing them with water; (d) removing water spots from the facing of the blankets; and (e) then drying the blankets.

17 Claims, No Drawings RUBBER PRINTING BLANKETS AND PROCESS FOR REMOVING AND CLEANING GLAZES THEREFROM BACKGROUND OF THE INVENTION In the process of carton making, lithographic rubber-faced blankets are used in connection with the printing of the cartons, the latter of which are generally made from carton board. For example, the blankets are utilized in the printing of cereal boxes. Such blankets are generally formed with two to six plies of fabric adhered together by specially compounded rubber or rubber-type materials, on top of which is adhered a rubber (natural, synthetic, or combination ofsame) facing ap proximately 0.02 inchesthick. In the course of the printing, the rubber facing of the blankets becomes glazed, preventing proper transfer of ink during print. This glaze includes ink glaze, stock glaze, and gum glaze. Thus, at the end ofeach run of a particular carton the blankets must be cleaned so as to remove the glaze for the next run. After a while these blankets become glazed to the point where they cannot be cleaned by the conventional manner, thereby becoming incapable of further proper transfer of the ink. At this point, replacement blankets must be purchased.

One attempt to overcome this problem has been to scrub the blankets very hard in the conventional cleaning to reduce the glaze, but this solution only extends the useful life of the blanket a little more than otherwise possible.

SUMMARY OF THE INVENTION The present invention relates to the removal of strongly adhering glaze from such blankets so as to allow them to be used for considerably longer period of time than heretofore possible. Specifically, the invention provides a method for the removal of the glaze, the method comprising the steps of (a) soaking the blankets in a saturated water solution of at least one mineral acid salt in combination with either at least one organic acid or a saturated solution of potassium sodium tartrate for a sufficient time and at a sufficient temperature to cause all but a trace of the glaze to be removed; (b) thereafter removing the blankets from the solution and rinsing them with water; (c) thereafter removing water spots from the facing of the blankets; and (d) thereafter drying the blankets.

Accordingly, it is an object of the invention to provide a process which will remove heavy glaze from a printing blanket so as to allow its continued reuse.

It is a related object of the invention to provide a process of the above character which is inexpensive and requires a minimum oftime.

lt is still another object of the invention to provide a process ofthe above character which has no harmful side effects upon the physical construction of such a blanket.

Other objects and advantages will become apparent upon reference to the following detailed discussion.

DESCRIPTION OF THE PREFERRED EMBODIMENT This invention relates to a process for the removal and cleaning of heavy glaze from rubber-faced printing blankets, which glaze heretofore has not been found to be easily removable. More particularly, 1 have found that soaking the blankets in a hot (preferably saturated) water solution of a mineral salt such as sodium bisulfate (Na H80 in combination with either an organic acid such as citric, tannic, or tartaric acid, or with a solution (again, preferably saturated) of potassium sodium tartrate (K Na C H -4 H O) is effective in removing substantially all of the glaze without having an adverse effect on the blankets.

Generally, the process incorporates the following steps: the blankets to be cleaned are wiped clean of ink by any suitable conventional cleaner. These are then placed in the soaking tank, which, for economy of treatment, should be large enough to accommodate more than one blanket. The blankets are preferably hung vertically within the tank so that they are completely submerged by the solution noted above. The blankets can be hung from their customary mounting bars, the

horizontal spacing between blankets preferably being between 1 and 2 inches. The bath is a water solution of a mineral acid salt and/or an organic acid. For example, approximately 5 percent by weight solution potassium sodium tartrate and approximately 5 percent by weight solution sodium bisulfate has been found to work satisfactorily. During the soaking, the temperature of the bath is preferably maintained just below boiling, most preferably in the range of about 200-212 F. The cooler the temperature of the bath, the longer the period of soaking necessary, thereby reducing the efficiency of the process. In the range specified above, the soaking should be maintained for a period of at least approximately 45 minutes. After the soaking, the blankets are removed and rinsed with water for a period of approximately 5 seconds or more, and thereafter the water spots are removed from the facing of the blankets, such as by wiping the facing with a fast-drying solvent such as isopropyl alcohol. The blankets are then dried by being hung vertically, thus insuring that no fabric impressions are formed in the rubber during the drying.

The use of a saturated solution of the salt is based upon the fact that such a solution remains at a constant strength during several soakings of different blankets. As the salt is used up, more should be added to maintain the bath at a saturated condition.

It has been found that this process is effective in removing substantially all the glaze without breaking down the adhesive holding the various plies together and without any other harmful side effects. Although the blanket swells slightly during the soaking, on drying it returns substantially to its normal thickness.

EXAMPLE NO. 1

A heavily glazed blanket was partially immersed in a solution of equal amounts of potassium sodium tartrate solution and sodium bisulfate solution, the concentrations of each being about 5 percent by weight and providing together a solution having a pH of approximately 1.9. The immersion was only partial and was maintained for approximately l hour with the temperature of the solution maintained at approximately 200 F. Afterwards, the blanket was dried and the untreated portions calipered at 0.0660 to 0.0665 of an inch, while the treated portion calipered at 0.0685 to 0.0690 of an inch. No difference was seen under a microscope between the treated printing areas and the treated nonprinting areas, indicating that only a trace of glaze was left. The blanket was mounted on a press and the treated areas transferred ink satisfactorily.

EXAMPLE NO. 2

A blanket which had been utilized to make approximately 415,000 impressions was slightly embossed and bore a medium to heavy glaze. This blanket was soaked in a solution similar to that set forth in the first example, the temperature however being maintained between F. and F. Removal of the blanket after 60 minutes indicated that cleaning was not quite complete on one side so that soaking was continued for 15 minutes more. Thereafter, the blanket was removed and washed with a conventional blanket wash twice and with water also. A short period of soaking in cold water was utilized to rinse the backing. The blanket was rubbed dry and hung to complete the drying. Thereafter, the blanket was used successfully for a total of about 200,000 additional impressions before it physically broke down. Thus, the process extended the life of the blanket approximately 50 percent.

Other combinations of chemicals have been found to work relatively satisfactorily. For example, when the bath was composed of a saturated solution of sodium sulfate combined with tannic acid and tartaric acid, each having a concentration of about 5 percent by weight, the glaze removal was substantially complete. Also, good results were obtained by using in combination with either citric acid, tannic acid, tartaric acid, or potassium sodium tartrate, a mineral acid salt selected from the following chemicals: sodium bisulfate, sodium bisulfite,

antimony potassium tartrate, aluminum potassium sulfate, and sodium thiosulfate. Finally, substantial removal of the glaze can be obtained by using an approximately 5 percent by weight concentration in water of citric acid, or tannic acid, or tartaric acid alone.

Iclaim:

l. A method of removal of glaze from rubber-faced printing blankets comprising the steps of:

a. soaking the blankets in a water solution of an effective amount of a material selected from the group consisting of:

l. at least one mineral acid salt in combination with either at least one organic acid or a substantially saturated solution of potassium sodium tartrate, and

2. an acid selected from the group consisting of citric acid, tartaric acid, and tannic acid;

for a sufficient time and at a sufficient temperature to remove at least some ofthe glaze by the action of the solution,

b. thereafter removing said blankets from said solution and rinsing them with water,

c. thereafter removing any water spots from the facing of said blankets, and

d. thereafter drying said blankets.

2. A method for removal of glaze from rubber-faced printing blankets comprising the steps of:

a. soaking the blankets in a water solution including an acid selected from the group consisting of citric acid, tartaric acid, and tannic acid, the acid in the solution being present in an amount producing a concentration of same of approximately 5 percent by weight, for a sufficient time and at a sufficient temperature to remove at least some ofthe glaze by the action ofthe acid,

b. thereafter removing said blankets from said acid solution and rinsing them with water,

c. thereafter removing any water spots from the facing of said blankets, and

d. thereafter drying said blankets.

3. A method for removal of glaze from rubber-faced print ing blankets comprising the steps of:

a. wiping ink from the blankets,

b. soaking said blankets in a water solution of approximately 5 percent by weight potassium sodium tartrate and ap proximately 5 percent by weight sodium bisulfate for a period of approximately 45 minutes to approximately 1 hour and at a temperature slightly below 212 F. to cause all but a trace of the glaze to be removed by the action of the solution, with said blankets hanging vertically in said solution,

. thereafter removing said blankets from said solution and rinsing them with water,

d. thereafter removing water spots from the facing of said blankets, and e. thereafter drying said blankets.

4. A method of removal of glaze from rubber-faced printing blankets comprising the steps of:

a. soaking the blankets in a substantially saturated water solution of at least one mineral acid salt in combination with either at least one organic acid or a substantially saturated solution of potassium sodium tartrate for a sufficient time and at a sufficient temperature to remove at least some of the glaze by the action ofthe solution,

b. thereafter removing said blankets from said solution and rinsing them with water,

c. thereafter removing any water spots from the facing of said blankets, and

d. thereafter drying said blankets.

5. The method as defined in claim 4, wherein said soaking of said blankets is maintained for a period of approximately 45 minutes to approximately 1 hour.

6. The method as defined in claim 4, wherein the temperatures of the solution during said soaking step is maintained at slightly below the boiling point of the solution.

7. The method as defined in claim 4, wherein said solution consists ofap roximatel 5 ercent by wei ht potassium 8. The metiiod as deffiiedbn claim 4, wfierein the temperature of said solution with the blankets placed therein is maintained between l50 F. and the boiling point ofthe solution.

9. The method as defined in claim 4, and further including as a preliminary step prior to the soaking step, the step of wiping ink from said blankets.

10. The method as defined in claim 4, wherein said rinsing of said blankets is continued for a minimum of approximately 5 seconds.

11. The method as defined in claim 4, wherein said drying step includes the hanging of said blankets in a vertical position while drying.

12. The method as defined in claim 4, wherein said organic acid is selected from the group consisting of citric acid, tartaric acid, and tannic acid, the acid being present in a concentration ofabout 5 percent by weight.

13. A method as defined in claim 4, wherein said mineral acid salt is selected from the group consisting of sodium bisulfate, sodium bisulfite, aluminum potassium sulfate, and sodium thiosulfate.

14. The method as defined in claim 4, wherein said blankets are held vertically submerged in said solution during said soaking step.

15. The method as defined in claim 14, wherein each ofsaid blankets is horizontally spaced apart from its neighbors a distance of between approximately 1 and 2 inches.

16. The method as defined in claim 4, wherein said spot removal step includes the step of wiping the rubber facing of said blankets with a fast drying solvent inert to said blanket.

17. The method as defined in claim 16, wherein said solvent is isopropyl alcohol.

7 3 UNTTEE STATES PATENT @EETEE CERTHFKQATE @F @QRRECTKQN Patent No. 3, 642, 537 Daizod February 15, 1972 Inventofls) Fredrick Lo Garms It is certified that error appears in the above-identified patent and that said Letters Patont are hereby corrected as shown below:

Column 4, line 21,, after "potassium" insert sodium tartrate and approximately 5% by weight sodium bisulfate,

Signd and sealed this 29th day of August 1972.

(Si'fIAL) Attest:

EDWARD M.FLEYPGHMLJR. v ROBERT GOTTSGHALK Attesting Officer Commissionerof Patents 

2. an acid selected from the group consisting of citric acid, tartaric acid, and tannic acid; for a sufficient time and at a sufficient temperature to remove at least some of the glaze by the action of the solution, b. thereafter removing said blankets from said solution and rinsing them with water, c. thereafter removing any water spots from the facing of said blankets, and d. thereafter drying said blankets.
 2. A method for removal of glaze from rubber-faced printing blankets comprising the steps of: a. soaking the blankets in a water solution including an acid selected from the group consisting of citric acid, tartaric acid, and tannic acid, the acid in the solution being present in an amount producing a concentration of same of approximately 5 percent by weight, for a sufficient time and at a sufficient temperature to remove at least some of the glaze by the action of the acid, b. thereafter removing said blankets from said acid solution and rinsing them with water, c. thereafter removing any water spots from the facing of said blankets, and d. thereafter drying said blankets.
 3. A method for removal of glaze from rubber-faced printing blankets comprising the steps of: a. wiping ink from the blankets, b. soaking said blankets in a water solution of approximately 5 percent by weight potassium sodium tartrate and approximately 5 percent by weight sodium bisulfate for a period of approximately 45 minutes to approximately 1 hour and at a temperature slightly below 212* F. to cause all but a trace of the glaze to be removed by the action of the solution, with said blankets hanging vertically in said solution, c. thereafter removing said blankets from said solution and rinsing them with water, d. thereafter removing water spots from the facing of said blankets, and e. thereafter drying said blankets.
 4. A method of removal of glaze from rubber-faced printing blankets comprising the steps of: a. soaking the blankets in a substantially saturated water solution of at least one mineral acid salt in combination with either at least one organic acid or a substantially saturated solution of potassium sodium tartrate for a sufficient time and at a sufficient temperature to remove at least some of the glaze by the action of the solution, b. thereafter removing said blankets from said solution and rinsing them with water, c. thereafter removing any water spots from the facing of said blankets, and d. thereafter drying said blankets.
 5. The method as defined in claim 4, wherein said soaking of said blankets is maintained for a period of approximately 45 minutes to approximately 1 hour.
 6. The method as defined in claim 4, wherein the temperatures of the solution during said soaking step is maintained at slightly below the boiling point of the solution.
 7. The method as defined in claim 4, wherein said solution consists of approximately 5 percent by weight potassium
 8. The method as defined in claim 4, wherein the temperature of said solution with the blankets placed therein is maintained between 150* F. and the boiling point of the solution.
 9. The method as defined in claim 4, and further including as a preliminary step prior to the soaking step, the step of wiping ink from said blankets.
 10. The method as defined in claim 4, wherein said rinsing of said blankets is continued for a minimum of approximately 5 seconds.
 11. The method as defined in claim 4, wherein said drying step includes the hanging of said blankets in a vertical position while drying.
 12. The method as defined in claim 4, wherein said organic acid is selected from the group consisting of citric acid, tartaric acid, and tannic acid, the acid being present in a concentration of about 5 percent by weight.
 13. A method as defined in claim 4, wherein said mineral acid salt is selected from the group consisting of sodium bisulfate, sodium bisulfite, aluminum potassium sulfate, and sodium thiosulfate.
 14. The method as defined in claim 4, wherein said blankets are held vertically submerged in said solution during said soaking step.
 15. The method as defined in claim 14, wherein each of said blankets is horizontally spaced apart from its neighbors a distance of between approximately 1 and 2 inches.
 16. The method as defined in claim 4, wherein said spot removal step includes the step of wiping the rubber facing of said blankets with a fast drying solvent inert to said blanket.
 17. The method as defined in claim 16, wherein said solvent is isopropyl alcohol. 